The registration fee is reasonable, or possibly on the cheap side given
the typical costs
Sweden I assume there will be good vegan options at all meals, otherwise
it would be fair to allow unbundling the meals.
On the other hand, I'm not sure what's the point of the registration
period being 2 weeks for early bird and 2 months for the base price.
This creates an incentive to register only at the last minute, after one
has decided all other details of the trip.
As noted, travel and accommodation usually make a much bigger share of
the costs. It's soon too late to get the best prices, but I see on
Airbnb there are still hundreds of rooms in Stockholm centre which cost
less than the official accommodation for a single room, and a few dozens
which cost less than the double room price. I've not checked university
dorms/apartments but I think they start getting full already in August.